Marine sails have long been of such plan shape and so supported that, when flying and held in tension by wind, the sail assumes a cambered shape, commonly referred to as draft. In the case of a foresail, the leading edge or luff of the sail is supported from an elongated stay and is slightly arcuate, curving from the foot forwardly to an intermediate portion of the stay and thence aft to the head, and is secured to the stay member which slants upwardly and aft from the bow of the boat. In some cases, the stay member does not turn, and the luff of the sail is attached to the stay member by fasteners called snap hooks and, in such cases, reefing the sail to flatten it is difficult, especially when the sail is to be flattened as a result of reefing. In other cases, as in the now conventional roller furling systems, the stay member is made rotatable and use of the rotatable stay member has lead to roller reefing, the general state of the art being illustrated by the following U.S. Pat. Nos.:
______________________________________ 70,256 Peterson 3,611,969 Hood 4,196,687 Newick 4,248,281 Hood 4,526,122 Kluckhuhn 4,573,424 Clausin ______________________________________
While roller reefing to flatten the sail has become a popular concept, prior-art systems have not achieved success from a practical standpoint in the trade. Though rolling the luff of the sail will reef the sail, such reefing has heretofore been accompanied by undue fullness, with the formation of wrinkles and pleats in the sail. Hood 4,248,281 discloses a very important objective, sought to be accomplished by attaching only an intermediate portion of the luff to the rotatable stay member and securing the tack and head in such fashion that initial turning of the stay member causes only the intermediate portion of the luff to be rolled, the sail therefore being flattened before being reefed, leading to what has been called "lag reefing" of the sail. But systems according to that patent have failed in actual practice to achieve the desired advantages. As a result, it has become common practice to secure to the luff of the sail a sheet of polymeric foam material, typically a sheet of closed cell elastomeric foam, the foam piece having a thickness of 1/8 in. to 1/4 in. and being wider along an intermediate portion of the luff and tapering to narrow ends at the tack and the head. And this has become the practice even when the system of Hood 4,248,281 is employed. Though such use of added foam material provides improved roller reefing and flattening, use of the foam involves numerous disadvantages. First, as the luff is rolled, presence of the relatively thick foam material increases the roll diameter excessively, spoiling the air flow characteristics of the sail at the luff. Also, due to its excess weight, the foam material does not allow the sail to fill and draw properly in light air. With the foam sheet material secured to the sail by adhesive, there is a tendency for the foam material to become detached from the sail under the conditions of prolonged use of the sail. Further, over a period of use, the foam material tends to become compressed and crack and deteriorate. Finally, the foam material is unduly expensive. There has accordingly been a continuing demand for improvement in roller reefing.